<title>跳马问题</title><link href="http://hzoi.com/tomorrow.css" rel="stylesheet"><div class="ui existing segment"><pre><code><span class="pl-cm">/*</span>
<span class="pl-cm">5 9</span>
<span class="pl-cm">*/</span>
<span class="pl-cp">#include</span><span class="pl-cpf">&lt;cstdio&gt;</span><span class="pl-cp"></span>
<span class="pl-kt">int</span> <span class="pl-n">m</span><span class="pl-p">,</span><span class="pl-n">n</span><span class="pl-p">;</span>
<span class="pl-kt">int</span> <span class="pl-n">dx</span><span class="pl-p">[</span><span class="pl-mi">4</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-p">{</span><span class="pl-o">-</span><span class="pl-mi">2</span><span class="pl-p">,</span><span class="pl-mi">2</span><span class="pl-p">,</span><span class="pl-o">-</span><span class="pl-mi">1</span><span class="pl-p">,</span><span class="pl-mi">1</span><span class="pl-p">};</span>
<span class="pl-kt">int</span> <span class="pl-n">dy</span><span class="pl-p">[</span><span class="pl-mi">4</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-p">{</span><span class="pl-mi">1</span><span class="pl-p">,</span><span class="pl-mi">1</span><span class="pl-p">,</span><span class="pl-mi">2</span><span class="pl-p">,</span><span class="pl-mi">2</span><span class="pl-p">};</span>
<span class="pl-kt">int</span> <span class="pl-n">ans</span><span class="pl-p">,</span><span class="pl-n">visited</span><span class="pl-p">[</span><span class="pl-mi">21</span><span class="pl-p">][</span><span class="pl-mi">21</span><span class="pl-p">];</span>
<span class="pl-kt">void</span> <span class="pl-nf">dfs</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">x</span><span class="pl-p">,</span><span class="pl-kt">int</span> <span class="pl-n">y</span><span class="pl-p">){</span>
        <span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">x</span><span class="pl-o">==</span><span class="pl-n">m</span> <span class="pl-o">&amp;&amp;</span> <span class="pl-n">y</span><span class="pl-o">==</span><span class="pl-n">n</span><span class="pl-p">){</span>
                <span class="pl-n">ans</span><span class="pl-o">++</span><span class="pl-p">;</span>
                <span class="pl-c1">//printf(&quot;%d\n&quot;,ans);</span>
                <span class="pl-k">return</span><span class="pl-p">;</span>
        <span class="pl-p">}</span>
        <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">0</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;</span><span class="pl-mi">4</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">){</span>
                <span class="pl-kt">int</span> <span class="pl-n">nx</span><span class="pl-o">=</span><span class="pl-n">x</span><span class="pl-o">+</span><span class="pl-n">dx</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">],</span><span class="pl-n">ny</span><span class="pl-o">=</span><span class="pl-n">y</span><span class="pl-o">+</span><span class="pl-n">dy</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">];</span>
                <span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">nx</span><span class="pl-o">&lt;=</span><span class="pl-n">m</span> <span class="pl-o">&amp;&amp;</span> <span class="pl-n">nx</span><span class="pl-o">&gt;=</span><span class="pl-mi">1</span> <span class="pl-o">&amp;&amp;</span> <span class="pl-n">ny</span><span class="pl-o">&gt;=</span><span class="pl-mi">1</span> <span class="pl-o">&amp;&amp;</span> <span class="pl-n">ny</span><span class="pl-o">&lt;=</span><span class="pl-n">n</span> <span class="pl-o">&amp;&amp;</span> <span class="pl-o">!</span><span class="pl-n">visited</span><span class="pl-p">[</span><span class="pl-n">nx</span><span class="pl-p">][</span><span class="pl-n">ny</span><span class="pl-p">]){</span>
                        <span class="pl-n">visited</span><span class="pl-p">[</span><span class="pl-n">nx</span><span class="pl-p">][</span><span class="pl-n">ny</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span>
                        <span class="pl-c1">//printf(&quot;(%d,%d)-&gt;(%d,%d)\n&quot;,x,y,nx,ny);</span>
                        <span class="pl-c1">//getchar();</span>
                        <span class="pl-n">dfs</span><span class="pl-p">(</span><span class="pl-n">nx</span><span class="pl-p">,</span><span class="pl-n">ny</span><span class="pl-p">);</span>
                        <span class="pl-n">visited</span><span class="pl-p">[</span><span class="pl-n">nx</span><span class="pl-p">][</span><span class="pl-n">ny</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-mi">0</span><span class="pl-p">;</span>
                <span class="pl-p">}</span>
        <span class="pl-p">}</span>
<span class="pl-p">}</span>
<span class="pl-kt">int</span> <span class="pl-nf">main</span><span class="pl-p">(){</span>
		<span class="pl-n">freopen</span><span class="pl-p">(</span><span class="pl-s">&quot;horse.in&quot;</span><span class="pl-p">,</span><span class="pl-s">&quot;r&quot;</span><span class="pl-p">,</span><span class="pl-n">stdin</span><span class="pl-p">);</span>
		<span class="pl-n">freopen</span><span class="pl-p">(</span><span class="pl-s">&quot;horse.out&quot;</span><span class="pl-p">,</span><span class="pl-s">&quot;w&quot;</span><span class="pl-p">,</span><span class="pl-n">stdout</span><span class="pl-p">);</span>
        <span class="pl-n">scanf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d %d&quot;</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">m</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">n</span><span class="pl-p">);</span>
        <span class="pl-n">visited</span><span class="pl-p">[</span><span class="pl-mi">1</span><span class="pl-p">][</span><span class="pl-mi">1</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span>
        <span class="pl-n">dfs</span><span class="pl-p">(</span><span class="pl-mi">1</span><span class="pl-p">,</span><span class="pl-mi">1</span><span class="pl-p">);</span>
        <span class="pl-n">printf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d&quot;</span><span class="pl-p">,</span><span class="pl-n">ans</span><span class="pl-p">);</span>
        <span class="pl-k">return</span> <span class="pl-mi">0</span><span class="pl-p">;</span>
<span class="pl-p">}</span>
</cpde></pre></div>